Fixed Loan Repayment Schedule Calculator

A fixed loan repayment schedule calculator estimates the equal monthly payment and total interest for a loan with a fixed annual percentage rate and a set term. Enter the loan amount, APR, and term to see the scheduled payment and the interest implied by those inputs.

Formula

For a fully amortizing loan with equal payments each month, the scheduled payment is calculated using the standard fixed-payment formula:

Payment = P × r ÷ [1 − (1 + r)⁻ⁿ]

• P is the amount borrowed, in dollars.
• r is the monthly interest rate as a decimal, calculated as APR ÷ 1,200 when APR is entered as a percentage per year.
• n is the number of monthly payments, calculated as loan term in years × 12.
• Total interest is the monthly payment × number of payments − principal, in dollars.

The calculator uses the payment formula directly and displays the payment to the nearest cent. The total-interest expression uses the displayed payment and the full number of scheduled payments. Because monthly payments are rounded, that total can differ slightly from a lender’s exact amortization figures, especially on longer loans.

Worked Example

Using the calculator’s default inputs—$20,000 borrowed, 8% APR, and a five-year term—the monthly rate is 8 ÷ 1,200, or 0.0066667. The number of payments is 5 × 12 = 60.

Substituting into the payment formula gives:

$20,000 × 0.0066667 ÷ [1 − (1.0066667)⁻⁶⁰] = $405.53 per month

Total scheduled payments using that rounded monthly amount are $405.53 × 60 = $24,331.80. Subtracting the original $20,000 principal gives $4,331.80 in estimated total interest.

Assumptions

• The interest rate remains fixed for the entire term.
• Payments are level monthly payments, made at the end of each monthly period.
• Interest accrues monthly using APR divided by 12; the APR input is a percentage per year.
• The calculation excludes fees, taxes, insurance, PMI, escrow, late charges, and other amounts unless included in the loan amount or rate entered.

What a Fixed Repayment Schedule Means

A fixed repayment schedule sets out the amount and timing of payments over a stated loan term. For a conventional fully amortizing fixed-rate loan, the required principal-and-interest payment stays level each month, assuming the balance, rate, and payment terms do not change. The borrower can use the schedule to understand the planned cash outflow and how payments reduce the debt over time.

“Fixed payment” does not necessarily mean every amount on a bill is fixed. A mortgage payment, for example, may also include escrowed taxes or insurance, which can change independently of the loan’s principal-and-interest payment. Fees, optional products, and payment adjustments are also outside this calculator unless explicitly represented in its inputs.

How Payments Reduce the Balance

Each scheduled payment includes interest accrued since the prior payment and an amount applied to principal. At the beginning of a fully amortizing loan, the balance is larger, so more of the payment goes toward interest. As the principal balance falls, less interest accrues each period and a larger share of the same payment reduces principal.

For example, with the default figures, the first month’s estimated interest is about $133.33 ($20,000 × 0.0066667). The remainder of the $405.53 payment—about $272.20—reduces principal. Later payments have a different split even though the scheduled payment remains the same. The final payment may be adjusted by the lender to account for rounding, exact payment dates, or the precise interest calculation method.

When to Use the Estimate

This calculator is useful for understanding the basic payment mechanics or checking how the loan amount, rate, and term affect an estimated monthly obligation. It can also help distinguish the monthly payment from total interest: a longer repayment term generally spreads repayment over more months, while interest continues to accrue on the outstanding balance. The exact results depend on the real contract terms and payment schedule.

For a useful estimate, obtain the loan amount, APR, and repayment term from the lender’s written disclosure or offer, then enter those figures in matching units. APR is an annual percentage input, not a monthly percentage. If the lender quotes a term in months, divide it by 12 to enter years; for example, 48 months is four years. Do not add a monthly rate into the APR field.

Limits and Common Sources of Difference

This is a standard mathematical estimate for a fixed-rate, fully amortizing loan with regular monthly payments. It is not a complete contractual amortization schedule. Actual loan calculations may use specific day counts, payment dates, rounding policies, fees, or other terms that this simplified formula does not model. A variable-rate loan, interest-only period, balloon payment, irregular payment plan, or changing balance needs a different calculation.

• APR is not the monthly rate: the formula converts an annual percentage to a monthly decimal by dividing by 1,200.
• Term affects both payment and interest: use the full agreed term, not the number of years you hope to keep the loan.
• Do not treat total interest as total cost: this result excludes costs not represented by the principal and APR inputs.
• Rounding matters: the displayed payment is rounded to cents, while a lender may calculate from more precise values and adjust a final payment.
• Extra payments are not included: additional principal payments can change the balance and payoff timing, so this scheduled-payment estimate will no longer describe that path.

Frequently Asked Questions

Does a fixed loan payment stay the same every month?
For a fixed-rate, fully amortizing loan, the scheduled principal-and-interest payment is generally level when payments are made as agreed. Other bill components, such as escrow, may change, and the contract may specify adjustments or a final-payment correction.

Does a fixed payment mean the same amount goes to principal each month?
No. The scheduled payment can stay level while the principal and interest portions change. Early in repayment, interest usually takes a larger share; as the balance declines, more of each payment reduces principal.

Why is the lender’s payment different from this calculator?
The lender may include fees or other charges, use a different timing or interest convention, or round calculations differently. Check that the principal, APR, term, and payment frequency entered here match the lender’s figures.

Does this calculator include taxes or insurance?
No. It estimates principal and interest from the loan amount, APR, and term. Taxes, insurance, PMI, escrow, and fees are not included.

Can I use it for a variable-rate or interest-only loan?
Not as a complete schedule. Its formula assumes a fixed rate and equal payments that repay principal and interest over the term. A changing rate or interest-only period requires a model that accounts for those terms.

This result is an estimate, and the lender’s disclosure gives the exact figures.

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in p | Loan amount | $ | 20000 | 1 | 100000000
in apr | Interest rate (APR) | % | 8 | 0.01 | 100
in yrs | Loan term | years | 5 | 0.0833 | 50
out pmt | Monthly payment | $ | p * (apr / 1200) / (1 - (1 + apr / 1200) ^ -(yrs * 12)) | 2
out int | Total interest | $ | pmt * yrs * 12 - p | 2